Infostealer Dexter Targets Checkout Systems

Since data is the new digital currency, it is not uncommon to read about data stealers designed to collect users’ personally identifiable information (PPI) like credit cards, etc. So the entry of ‘Dexter’ in the threat picture comes as no surprise, especially as the holiday season draws near.

There are reports of a malware that targets point-of-sale (POS) systems used to store payment card data. Point-of-sale (like checkout counters) is typically where payment for goods and services occur. Given the wealth of data found on these payment hubs, it’s expected that these are the next targets of cybercriminal activities.

Dubbed ‘Dexter’ (Trend Micro detection BKDR_DEXTR.A), the malware was reportedly found in (POS) systems of popular establishments, hotels, and other businesses. Currently, the arrival infector remains undetermined. However, it is unlikely that the malware is downloaded from malicious sites, as the POS systems are typically not used for web browsing.

Based on our analysis of the malware, BKDR_DEXTR.A downloads files, sends information, and checks memory for information among others. But the centerpiece of the malware is its ability to collect and send certain information to a remote server. Some of the possible data that can be stolen from POS systems include such as username, hostname, key to decrypt the sent information, OS information, and list of running processes. These data are then presumably duplicated by remote malicious users.

The malware executable is found to be packed or encrypted and when loaded, it loads long garbage code to decrypt the actual code. However, this decryption routine involves only a combination of XOR and ADD instructions, with the use of a hardcoded key. The perpetrators behind ‘Dexter’ malware probably done this to make analysis difficult.

BKDR_DEXTR.A presents a new angle to data-stealing narrative. Unlike other notorious spyware such as ZeuS/ZBOT and SpyEye, the malware does not directly infect users’ systems to gather data like payment card details. Instead, the crooks behind BKDR_DEXTR figured that they can generate the same result by infecting certain POS systems.

In our 2013 Security Predictions, we foresee threats that can be found on home appliances like an Internet-connected TV. As new technology arrives and as users are more immersed into the digital lifestyle, we may soon find threats, like BKDR_DEXTR.A, in unexpected places that hit closer to home.